It is known to provide thin film coatings on substrates, for example metal substrates, by the deposition of the coating material from a plasma by plasma sputtering or the like. Such processes have generally required the use of a fixed apparatus located at the coating facility and hence the transport of the articles to be coated to the apparatus and the insertion of the articles into a coating chamber and removal of the coated articles from the coating chamber.
Such coatings are widely used for tribological treatments, i.e. treatments which decrease the coefficient of friction and coatings which protect the surfaces from environmental deterioration or wear.